John Deere CAB523672 – CAB: Pressurizer Fan Motor Open Circuit

The Cab Control Unit (CAB) has detected an open circuit in the pressurizer fan motor (circuit cc#921), specifically logged as FMI .05. The controller is sending power to the motor but does not detect the expected electrical load in return, preventing the fan from operating. This condition directly affects the heating, ventilating, and air conditioning (HVAC) system's ability to function properly.

• 9470 STS
• 9570 STS
• 9670 STS
• 9770 STS
• 9560 STS
• 9660 STS
• 9760 STS
• 9870 STS
• 9650 STS
• 9750 STS
• 9860 STS

1. 1

   Review the controller for any other active or stored fault codes that might indicate a broader electrical issue

2. 2

   For 9660 STS and 9760 STS models, check fuse F7 in the engine compartment relay panel (designated for Pressurizer Fan Power) - a blown fuse will cause an open circuit

3. 3

   Carefully inspect the wiring harness leading to the pressurizer fan motor, paying particular attention to wire cc#921, for chafing, breaks, or corrosion

4. 4

   Disconnect and inspect the electrical connector at the pressurizer fan motor for corrosion, bent, or pushed-out pins, and ensure it is securely seated upon reconnection

5. 5

   With the key on and the fan commanded on, check for voltage at the motor's electrical connector to verify power is reaching the motor

6. 6

   With the circuit de-energized, check the continuity of wire cc#921 from the Cab Control Unit to the motor connector to rule out a wire break, and measure the motor's internal resistance to compare to a known good part if specifications are available

1. 1

   Prepare machine for service

   Park the machine on a level surface, shut down the engine, engage the parking brake, and disconnect the battery before beginning any electrical repair work.

2. 2

   Locate pressurizer fan

   Locate the pressurizer fan, which is part of the cab's HVAC system. It is typically accessible through service panels on or around the cab structure.

3. 3

   Remove faulty motor

   Remove any required access panels. Disconnect the electrical connector, then unbolt and remove the old motor and squirrel cage assembly.

4. 4

   Install new motor

   Install the new pressurizer fan motor, ensuring it is securely mounted. If the new motor does not come with a fan cage, transfer the cage from the old motor.

5. 5

   Reassemble components

   Reconnect the electrical connector to the new motor and reinstall any access panels that were removed.

6. 6

   Test system operation

   Reconnect the battery. Turn the ignition on and activate the HVAC system to verify that the new pressurizer fan is operating correctly.

7. 7

   Clear fault codes

   Use the machine's diagnostic display to clear the stored CAB 523672.05 fault code. Run the system again to ensure the code does not reappear.